No spark / No start

[Jonah Hinz]

Need help on a 73 duster, slant six. I am not getting spark at the plugs and a sluggish engine crank. I have replaced battery, starter, starter relay, battery cables, ballists, starter, coil, condenser, distributor, distributor cap, rotor, spark plugs & wires, voltage regulator and igniton control module. coil is giving off spark but not real strong. Carb is getting fuel. what am I missing???

 

[motorpirate]

Any engine needs 4 things to run. SUCK/SQUEEZE/BANG/BLOW.
Compression.
Has to be in time.
Fuel
spark.
if it doesn't run one or more is missing.
Does it have compression? like even 75 lbs per cyl should be enough to "run".
Is it in time? are both valves closed when its at top dead center? Is the rotor pointed at the #1 plug wire?
is fuel getting to the cylinders? are the plugs wet with fuel?
If not, what if you spray carb cleaner in the carb while cranking?
or pull an easy plug and spray some in the cyl then re install the plug and try to start it?
You said it has spark at the coil, what about at the plugs?

 

[pishta]

Does distributor rotate when cranking, would prove timing chain is still in one piece. Get it to @tdc on first cylinder compression stroke and line up distributor event to tower #1. Even a weak spark will light it off, look at a lawnmower, about the same compression of a slant.

 

[dodge71demon]

there is two sides to ignition --run and crank - did you mess with the wiring any

 

[Slantsix64]

Does distributor rotate when cranking, would prove timing chain is still in one piece. Get it to @tdc on first cylinder compression stroke and line up distributor event to tower #1. Even a weak spark will light it off, look at a lawnmower, about the same compression of a slant.

Lol

 

[pishta]

What is gap of reluctor? .008?

 

[Jonah Hinz]

there is two sides to ignition --run and crank - did you mess with the wiring any

nothing but what I posted

 

[Jonah Hinz]

What is gap of reluctor? .008?

yes gapped .008

 

[Jonah Hinz]

Does distributor rotate when cranking, would prove timing chain is still in one piece. Get it to @tdc on first cylinder compression stroke and line up distributor event to tower #1. Even a weak spark will light it off, look at a lawnmower, about the same compression of a slant.

yes, timing chain is good and seems to be set correctly. cant tell exactly since it has to run for timing light

 

[67Dart273]

............Sigh...........Where do I start?

First, "sluggish cranking" you said. Of all the parts you threw at it does it crank good now? This is likely the first thing, because if you don't have a good battery/ cables/ starter, the ignition won't output good spark, either. So you have a "double hit".........the engine is cranking slowly, and the spark is poor. Either / both are a cause for poor/ no start

You have a multimeter? A second, good battery? test lamp? a couple/ few alligator jumper leads?

=========================================

Page teu, as Paul Harvey used to say

It is important to understand the ignition power circuit. The key provides direct battery power to the coil/ ignition during cranking, so that you get a better spark. If you say, are cranking it by jumpering the starter relay, YOU WILL NOT HAVE a strong spark, because the ignition will still be going through the ballast resistor.

=========================================

You NEED a meter and learn how to use it. You cannot "look" at cables/ clamps/ connections, and hope/ wish/ fantasize that they are good, bad, working, or not. VERY possible that a simple dirty cable clamp is all that is wrong here. Learn to use a meter!!!!

Put one probe of the meter DIRECTLY onto the battery PLUS post. Stab the other onto the clamp. jumper the relay and crank the engine, and read the meter. Should read almost zero, the lower the better. This shows you have NO voltage drop across the clamp. Now leave the meter on the post, move down to the starter stud. Crank it again. Should only have maybe, 3.--.4V (4/10 of one volt) or LESS across the cable.

Do same test on the NEG cable.

Now double check your test. Stab the probes into the battery posts Jumper the starter relay and read the meter. NOTE the voltage. You need MINIMUM 10.5V the more the better

Now move the meter leads----clip them to a ground on the block (such as carb stud) and to the starter stud. Crank the motor, read the meter. Should only be maybe......3--.5V max difference between the battery reading and this reading. Again, you want MINIMUM 10V better 10.5 or more

 

[67Dart273]

Ignition troubleshooting



Here's a post I made about the simplest way I know to get across testing the ECU/ ignition parts This was intended to be educational so you understand how it all hooks up

You need a coil, the ECU and the distributor (and a battery)

Lay it out on the bench. Follow the diagram. Find the two distributor pickup terminals on the ECU. Hook them to the distributor

Hook the ECU case to battery NEG

Coil does NOT need grounded

Distributor does NOT need grounded.

Hook coil + to the power lead terminal on the ECU. Get a clip lead hooked there and let dangle. This is your battery "hot" when you are ready

Hook something from coil "case" to a probe for testing spark.

Hook up your power clip lead. Twist the distributor shaft while holding the test probe near the coil tower. The thing should make sparks

If not, unhook distributor. Take first one, then the other pickup clip leads, and "tap tap" ground them at the battery connection. Coil should make 1 spark each time you do so.

If not, try another coil. If that does not fix it replace the ECU

IF you hook it all up and it WORKS, then there is something AFU in the car harness. SUSPECT a bad ECU connector OR a bad DISTRIBUTOR connector
=============================================
This is all you need to test the basics of the ignition. You can easily test the ballast separate. A battery, the ECU, distributor and a coil, and of course some test leads

(copy image location......................)

Below, the basic diagram for a 4 pin ECU

Below, the wire for testing spark. I use my 12V test light. No, LOL the spark won't blow up the bulb

Below, the ground connection. ALL you need is one wire from batt NEG to the ECU case

Below, the two distributor connections. In the car these are polarity sensitive, but for testing does not matter

Below, the coil NEG connection

Below, battery PLUS connection, one wire to this terminal of ECU and jumpered over to + side of coil

Below, all hooked up and ready to test (except for battery ground). Should produce sparks at least 3/8" and typically 1/2" long

Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)

 

[pishta]

Point distributor is a good test tool....Electronic ignition is nice but if it stops, the "voodoo that they do" is somewhat a mystery as your staring at it on the side of the road. Its one bolt to replace a distributor in the field. I've kept a points distributor in the tool box since my 2nd MSD box went south on me on the road. Have not had to use it yet with the Mallory "Mighty 690" box.

 

[BillGrissom]

How did you judge the "no spark"? Unless you used an in-line spark tester ($3 Harbor Freight) you may just be inferring. I 2nd 67Dart273. Make a bench-test of components w/ distributor removed so you can spin it by hand. Start off by charging & discharging the coil by just using an alligator clip (hold w/ rubber so you don't get zapped). If that doesn't give a spark, your coil or battery is bad. If you can't get anything from the Mopar ECU, you can change to a GM 8-pin HEI module which lets you drop the ballast and get a stronger spark. Many posts.

 

[67Dart273]

That's pretty good. The point you made about the "single ground" is good. Many wrongly think the coil and or distributor (breakerless) need grounded

Couple of minor points:

The ECU should not be powered off the coil side of the ballast but rather run direct to the battery. I don't even use a ballast for short tests, I just make sure not to leave the coil powered for long

It would be a good idea LOL, NOT to put the ballast on a plastic backing as shown.

You might have mentioned, or maybe I misunderstood, (some folks might not) that the test lamp is simply acting as a probe. I just use it sometimes because it makes a handy probe. Most of the time I try to find my Lisle spark tester, which is adjustable.

 

[GTS Dave]

That's pretty good. The point you made about the "single ground" is good. Many wrongly think the coil and or distributor (breakerless) need grounded

Couple of minor points:

The ECU should not be powered off the coil side of the ballast but rather run direct to the battery. I don't even use a ballast for short tests, I just make sure not to leave the coil powered for long

It would be a good idea LOL, NOT to put the ballast on a plastic backing as shown.

You might have mentioned, or maybe I misunderstood, (some folks might not) that the test lamp is simply acting as a probe. I just use it sometimes because it makes a handy probe. Most of the time I try to find my Lisle spark tester, which is adjustable.

Gotcha. I will make the adjustments and do another video.

Thanks.

 

[GTS Dave]

Ok, here's an updated snapshot of setup and video link. Hope this works better.

thanks

Here's the YouTube link..